Magnetic disks, as well as magnetic heads used for writing and reading data to and from magnetic disks are tested in relation to their characteristics by a test system before being mounted to magnetic disk systems (see, for example, JP-A No. 268955/2006). Magnetic head test is performed in the form of head gimbal assembly (HGA) in which a head-suspension and a magnetic head are assembled together. At the time of testing, a magnetic head is located above a magnetic disk rotated by a rotating spindle to write and read data to and from the magnetic disk.
A piezoelectric actuator is often used as an actuator for precise positioning. In general, the displacement of the piezoelectric actuator is about several μm to 20 μm. In order to make the displacement of the fine actuator bigger than the above range, a displacement magnifying mechanism can be used to mechanically increase the displacement. A lever, which is well known as the fundamental principle, can be applied to increase the displacement of the piezoelectric actuator (see, for example, JP-A No. 48955/2004).
Further, in this test system, a second fine actuator may be mounted on a first fine actuator (see, for example, JP-A No. 268955/2006). In this case, the first fine actuator can be used to let the magnetic head to follow the eccentricity.